Tropical Storm MAYSAK Advisory 8月29日

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 10W (MAYSAK)
WARNING NR 04//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL STORM (TS) 10W (MAYSAK), LOCATED APPROXIMATELY 588 NM SOUTH OF KADENA AB, HAS TRACKED WEST-NORTHWESTWARD AT 05 KNOTS OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED SATELLITE IMAGERY AND A 281734Z AMSR2 89GHZ MICROWAVE IMAGE DEPICT AN ELONGATED LOW LEVEL CIRCULATION CENTER (LLCC) PARTIALLY OBSCURED BY DEEP CONVECTION WITH CONVECTIVE BANDING ALONG THE SOUTHERN AND WESTERN PERIPHERY OF THE DISTURBANCE. THE INITIAL POSITION IS PLACED WITH FAIR CONFIDENCE BASED ON THE BROAD, ELONGATED LLCC IN THE EIR SATELLITE LOOP AND A 281901Z SSMI 85 GHZ MICROWAVE IMAGE. THE INITIAL INTENSITY OF 45 KTS IS PLACED WITH HIGH CONFIDENCE BASED ON MULTIAGENCY DVORAK CURRENT INTENSITY ESTIMATE OF T3.0 (35-45 KTS) FROM RJTD, A T3.0 ADVANCED DVORAK TECHNIQUE ESTIMATE FROM 281800Z AND A SATCON ESTIMATE OF 44 KNOTS FROM 281653Z. ENVIRONMENTAL CONDITIONS REMAIN FAVORABLE FOR FURTHER DEVELOPMENT WITH MODERATE DIVERGENCE ALOFT AND VERY WARM (30-31 CELSIUS) SEA SURFACE TEMPERATURES (SST) OFFSET SLIGHTLY BY LOW TO MODERATE (10-20 KTS) VERTICAL WIND SHEAR (VWS) AND CONVERGENT FLOW FROM A WESTWARD PROPAGATING TROPICAL UPPER TROPOSPHERIC TROUGH (TUTT) CELL POSITIONED TO THE EAST-NORTHEAST OF THE SYSTEM. IN ADDITION TO WARM SST, OCEAN HEAT CONTENT (OHC) REMAINS HIGH (GREATER THAN 125 JOULES PER SQUARE CENTIMETER). THE SYSTEM IS TRACKING SLOWLY IN A WEAK STEERING ENVIRONMENT INDUCED BY AN EXTENSION OF A NEAR EQUATORIAL RIDGE POSITIONED TO THE SOUTHEAST OF THE SYSTEM AND A BUILDING SUBTROPICAL RIDGE TO THE EAST.
3. FORECAST REASONING.
   A. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS
PROGNOSTIC REASONING MESSAGE.
   B. TS MAYSAK WILL BEGIN A SLOW, GENERALLY NORTHWARD TURN OVER THE NEXT 12 HOURS AS A REORIENTATION OF THE STEERING RIDGES TAKES PLACE. THE ENVIRONMENT WILL REMAIN HIGHLY FAVORABLE FOR INTENSIFICATION WITH VERY WARM SST, ROBUST EQUATORWARD OUTFLOW AND LOW (< 10 KTS) VWS. ADDITIONALLY, THE AFOREMENTIONED WESTWARD PROPAGATING TUTT CELL POSITIONED TO THE NORTHEAST OF THE SYSTEM WILL BEGIN TO ENHANCE THE POLEWARD OUTFLOW. THESE CONDITIONS WILL LEAD TO RAPID INTENSIFICATION OF THE SYSTEM AS IT TRACKS NORTHWARD ALONG THE BUILDING STR, LEADING TO AN INTENSITY OF 75 KTS BY TAU 24. AS THE SUBTROPICAL RIDGE CONTINUES TO REORIENT, THE SYSTEM WILL TRACK GENERALLY NORTHWARD THROUGH TAU 48 AND FURTHER INTENSIFY TO 95 KTS. AFTER TAU 48, TS MAYSAK WILL BEGIN A GENERALLY NORTH-NORTHWESTWARD TRACK ALONG THE WESTERN PERIPHERY OF THE STEERING RIDGE. CONDITIONS ARE FORECAST TO REMAIN HIGHLY FAVORABLE FOR FURTHER INTENSIFICATION AND LEAD TO A PEAK INTENSITY OF 110 KTS BY TAU 72. NUMERICAL MODEL SOLUTIONS STILL SHOW A SIGNIFICANT DIVERGENCE WITH A MAXIMUM CROSS TRACK SPREAD OF 170 NM AT TAU 72. AT THIS TIME, ECMWF, JGSM AND UKMET ALL CONVERGE WEST OF THE JTWC MULTIMODEL CONSENSUS, WHILE THE GFS (DETERMINISTIC AND ENSEMBLE) AND AFUM TRACKS LIE TO THE EAST. THE JTWC FORECAST TRACK IS HEDGED TO THE WEST OF THE MULTIMODEL CONSENSUS BASED ON THE CONVERGENCE OF THE AFOREMENTIONED SOLUTIONS. DUE TO THE LARGE SPREAD IN SOLUTIONS, THERE IS ONLY FAIR CONFIDENCE IN THE INITIAL (TAU 0-72) PORTION OF THE JTWC FORECAST TRACK.
   C. IN THE EXTENDED PERIOD, THE AFOREMENTIONED STEERING RIDGE WILL CONTINUE TO REORIENT AND DEEPEN AFTER TAU 72 AND BECOME THE PRIMARY STEERING MECHANISM OF TS 09W. THIS WILL LEAD TO A GENERALLY NORTHWESTWARD TRACK FROM TAU 72 TO TAU 96. DURING THIS TIME, SSTS WILL BEGIN TO COOL SLIGHTLY. DESPITE THIS, THE SYSTEM WILL MAINTAIN AN INTENSITY OF 110 KTS AS IT REACHES THE STR AXIS
BY TAU 96 DUE TO FAVORABLE SHEAR AND OUTFLOW CONDITIONS. AT TAU 96, TS MAYSAK WILL ROUND THE STR AND BEGIN TO ENTER COOLER WATERS AND INCREASING VWS. THESE CONDITIONS, COUPLED WITH DECREASING DIVERGENT FLOW ALOFT DUE TO AN INCOMING SHORTWAVE TROUGH IN THE UPPER LEVELS, WILL LEAD TO GRADUAL WEAKENING TO 90 KTS BY TAU 120. THE CONTINUED SPREAD IN MODEL SOLUTIONS LENDS ONLY OVERALL FAIR CONFIDENCE IN THE OVERALL JTWC FORECAST TRACK.//
NNNN
NNNN